A wave of recalls stemming from a Crookston sunflower processing plant grew even bigger this week, with General Mills, Kellogg and Quaker Oats all recalling granola bars containing sunflower nuts potentially tainted with listeria.

The number of recalls associated with sunflower nuts processed at SunOpta's Crookston plant has reached double digits over the past month, spanning the country and involving well over 100 products.

General Mills on Thursday announced a voluntary recall of four flavors of its Nature Valley Protein Chewy Bars and Nature Valley Simple Nut Bars. The Golden Valley-based packaged food giant said the recall is "part of sunflower kernel supplier SunOpta's ongoing national recall."

Also Thursday, Quaker Oats announced a second voluntary recall of its Quaker Quinoa Granola Bars. Earlier this week, Kellogg's Kashi division voluntarily recalled one variety of its namesake granola bars as well as one type of its Bare Naked Granola. Both companies cited SunOpta sunflower nuts.

In another recall Thursday, Clif Bar recalled three varieties of its snack bars, also citing sunflower nuts sourced from SunOpta.

No illnesses have been reported in conjunction with the recalls. Listeria is a type of bacteria that can cause a potentially deadly infection, and it strikes hardest at pregnant women, newborns, older adults and people with weakened immune systems.

Toronto-based SunOpta is an ingredient supplier specializing in natural and organic products. The company's U.S. headquarters is in Edina, and it has several plants in Minnesota.

In the first week of May, SunOpta itself recalled sunflower nuts that it had packaged under the Planters brand, as well as a regional brand, Dakota's Best Biggy'z. SunOpta would expand its own recall twice — on May 18 and June 1 — and include the Sunrich brand that it also packages. The expanded recalls coincided with a lengthening of the production period in which the potential listeria contamination occurred.

Since SunOpta is a significant ingredient supplier, potentially tainted sunflower nuts spread through the food system, prompting recalls. Companies making recalls have included Treehouse Foods, one of the nation's largest private label food makers, and Kroger. A supplier to Trader Joe's also made a recall due to SunOpta ingredients.

SunOpta discovered the listeria problem from one of its customers, which had tested a batch of sunflower seeds that came up positive for listeria. Because of the listeria issue, the Crookston plant was closed April 21 and did not reopen until Wednesday.

"We are confident that through our work, in conjunction with external experts, we identified and eliminated the root causes of the contamination and therefore resumed production," SunOpta CEO Rik Jacobs said in a statement.